cannot display thread result on a textbox

[warjie]

Cross-thread operation not valid: Control 'textBox1' accessed from a thread other than the thread it was created on

i usually get this error,,i want to display the thread result to a textbox but i just can't..please help me,,thanks a lot

here's my code:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Threading;

namespace MultiThread
{
    public partial class Form1 : Form
    {
        Thread thread;
        public Form1()
        {
            InitializeComponent();
        }
        
        // delegate is used to communicate with UI Thread from a non-UI thread
        //public delegate void UpdateTextCallback(string message);

        private void Form1_Load(object sender, EventArgs e)
        {
            
        }
        
        private void button1_Click(object sender, EventArgs e)
        {
            // Creates a new thread
            thread = new Thread(new ThreadStart(TestThread));
            thread.IsBackground = true;
            thread.Start();
 
        }

        private void Form1_FormClosing(object sender, FormClosingEventArgs e)
        {
            thread.Abort();
        }

        private void TestThread()
        {
            for (int i = 0; i <= 1000; i++)
            {
                //Thread.Sleep(1000);
                textBox1.Text = textBox1.Text + "Thread";
                //textBox1.BeginInvoke(new UpdateTextCallback(UpdateText), new object[] { i.ToString() });
                Thread.Sleep(100);
            }
        }

        private void UpdateText(string message)
        {
            textBox1.Text = message;
        }
    }
}

[Raj K]

Use this code to update the text box

this.BeginInvok e(new Action(delegate () {textBox1.Text = textBox1.Text + "Thread";}) );